Wireless access apparatus and method for long and narrow channel

Abstract

The application discloses a kind of long and narrow channel-oriented wireless access device and method, device includes a plurality of sequentially connected access point units, access point unit includes: directional antenna, for realizing the signal coverage of specified channel area;Photoelectric converter group, for completing the photoelectric / electro-optical conversion of serial signal;Environment sensor, for monitoring the environment in channel;Central processing unit, for receiving, processing and forwarding data;External interface, for the connection of host computer and central processing unit, realizes data transceiving;Access point unit is connected by photoelectric converter group each other.The long and narrow channel of the application is split into multiple sections, each long and narrow channel is covered by directional antenna on wireless access device, and wireless access device is connected by optical fiber, supports multiple connection modes, designs special network configuration frame, solves the problem that existing wireless router or base station is high in cost and poor in reliability in long and narrow channel environment.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication, and relates to wireless network access and mobile terminal positioning, specifically to a wireless access device and method for narrow channels. Background Technology

[0002] Wireless communication within narrow passages (such as tunnels) faces multiple technical challenges. The core issue lies in the limitations imposed by the enclosed and narrow physical structure of the passage on radio frequency signal propagation: Firstly, signal attenuation is severe, and the inner walls of the passage are often made of concrete or metal, hindering the propagation of 4G / 5G and WiFi signals. First, wireless signals are easily reflected and absorbed during propagation. In long-distance scenarios, signal strength decreases exponentially with transmission distance, often resulting in signal interruption within tens of meters. Second, multipath effects are significant. After being emitted from the transmitter, the signal reaches the terminal through multiple paths, such as the tunnel walls and the ground. The superposition of signals from different paths can easily cause phase cancellation, leading to signal fluctuations and data packet loss at the receiving end. Third, coverage blind spots are difficult to eliminate. Special locations such as bends, entrances and exits, and equipment wells in the tunnel can easily create signal obstruction dead zones, making it impossible to achieve uniform coverage with conventional base station deployments. Fourth, electromagnetic interference and environmental adaptability are poor. Electromagnetic interference generated by trains passing through the tunnel and the operation of electrical equipment can degrade communication quality and reduce the stability of wireless links, making it difficult to meet the needs of emergency communication and robot control. Fifth, environmental factors such as high temperature, vibration, and humidity in the tunnel can easily cause port loosening and fiber optic damage, threatening the reliable operation of wireless access equipment. Moreover, the manpower cost of equipment maintenance in narrow tunnels is high.

[0003] Existing wireless access solutions are mostly based on wireless routers or mobile base stations, using fiber optic interconnection and omnidirectional antenna coverage, and completing data transmission and reception via Ethernet packets. Although such devices can provide high bandwidth, they suffer from poor stability and high cost, and cannot be adapted to narrow channel application scenarios with low bit rate, high reliability, long distance, and cost sensitivity. Summary of the Invention

[0004] Purpose of the invention: In order to solve the problems of high deployment cost and poor reliability of existing wireless routers or base stations in narrow and long corridor environments, a wireless access device and method for narrow and long corridors is provided, which realizes high cost-effectiveness and high reliability wireless network coverage in narrow and long corridors, and has the advantages of low cost, high reliability, flexible networking and easy node configuration.

[0005] Technical Solution: To achieve the above objectives, the present invention provides a wireless access device for narrow channels, comprising a plurality of access point units connected in sequence, wherein the access point unit includes:

[0006] Directional antennas are used to achieve signal coverage in a specified channel area;

[0007] A photoelectric converter group is used to perform photoelectric / electro-optical conversion of serial signals;

[0008] Environmental sensors are used to monitor the environment within the channel;

[0009] The central processing unit (CPU) is used to receive, process, and forward data.

[0010] The external interface is used to connect the main control computer and the central processing unit to realize data transmission and reception.

[0011] The access point units are interconnected through photoelectric converter groups.

[0012] Furthermore, the directional antenna is connected to the radio frequency chip, which is used to amplify and modulate the signal, and convert the radio frequency signal into a digital signal that can be recognized by the I / O port, and provide it to the central processing unit.

[0013] Furthermore, the photoelectric converter group includes at least one pair of optical fiber transceiver ports and one pair of electrical transceiver ports.

[0014] Furthermore, the photoelectric converter groups are interconnected via optical fibers, thereby enabling the sequential connection of access point units.

[0015] Furthermore, the connection methods of the access point units include simple series, parallel series, bidirectional series, and hybrid series, wherein:

[0016] Simple cascading: Each access point unit uses only one pair of fiber optic ports for cascading.

[0017] Parallel serial connection: Each access point unit uses multiple pairs of fiber optic ports connected in parallel, with the data flow direction being the same.

[0018] Bidirectional serial connection: Each access point unit uses two pairs of fiber optic ports for bidirectional serial connection, with data flow directions in opposite directions;

[0019] Hybrid cascading increases the number of optical fibers connected to access point units that are difficult to maintain, based on simple cascading.

[0020] The present invention also provides a method for accessing a wireless access device. When a mobile terminal approaches an access point unit K, it establishes a bidirectional wireless connection with the access point unit K. Data is transmitted bidirectionally through a wireless channel and forwarded to each other by access point units connected by optical fibers, thereby realizing communication between the mobile terminal and the host computer.

[0021] Furthermore, the communication process and forwarding rules between the mobile terminal and the main control computer are as follows:

[0022] A1: When the mobile terminal approaches the access point unit K, it sends uplink data to the access point unit K through the radio frequency link and receives downlink data from the access point unit K through the radio frequency link.

[0023] A2: Any access point unit determines the data forwarding direction based on the network topology and completes the data forwarding;

[0024] A3: When the access point unit K, which is directly connected to the main control computer, receives data, the central processing unit sends the data to the main control computer through the external interface.

[0025] Furthermore, in step A1, the mobile terminal achieves positioning by measuring the signal power of different access point units, that is:

[0026]

[0027] in, , These are the signal power measured by the mobile node to access point m and access point n, respectively. This is the coefficient for signal attenuation with distance. The distance between access points m and n and These represent the distances between the mobile terminal and access points m and n, respectively, which are the one-dimensional positioning results.

[0028] Furthermore, obtaining the network topology in step A2 includes:

[0029] The master computer sends a network test command, enabling all access point units to obtain complete network topology information, specifying the shortest hop count, and defining the process and forwarding rules as follows:

[0030] B1: The main control computer connects to the access point unit K. The access point unit K outputs a network test frame header and adds its own ID.

[0031] B2: After receiving the network test frame, other access point units add their own ID and forward it to the next level;

[0032] B3: Access point unit K terminates forwarding when it observes its own ID twice from the received network test frame;

[0033] Any access point unit can determine the distance to the target access point by receiving network test frames, that is, the distance between its own ID and the target access point ID.

[0034] Beneficial Effects: Compared with existing technologies, this invention uses directional antennas, multiple pairs of photoelectric converters, a central processing unit, a radio frequency chip, and sensors as key modules to divide long, narrow channels into multiple segments. Each segment is covered by a directional antenna on a wireless access device, which is then connected via optical fiber. The complementary characteristics of each optical interface are utilized to improve network reliability and reduce data latency, while supporting multiple networking methods. The system design avoids expensive high-speed optical modules and high-speed signal processing chips, reducing equipment costs. This invention achieves high-performance, cost-effective, and highly reliable wireless network coverage in narrow channels, providing a convenient networking method for mobile terminals and monitoring equipment in tunnels, mine shafts, underground passages, and bridge tunnels. Attached Figure Description

[0035] Figure 1 This is a structural diagram of a single access point unit;

[0036] Figure 2 This is a schematic diagram of different serial connection methods in a wireless access device;

[0037] Figure 3 This diagram illustrates how wireless access devices in different serial configurations obtain topology information by transmitting and receiving network test frames.

[0038] Figure 4 This is a schematic diagram of wireless positioning for a mobile terminal. Detailed Implementation

[0039] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0040] Example 1:

[0041] This embodiment provides a wireless access device for narrow channels, including multiple access point units connected in sequence, such as... Figure 1 As shown, the access point unit includes:

[0042] Directional antennas are used to achieve signal coverage in a specified channel area;

[0043] A photoelectric converter group is used to perform photoelectric / electro-optical conversion of serial signals;

[0044] Environmental sensors are used to detect sound, light, and images within the tunnel and monitor the environment inside the tunnel.

[0045] The central processing unit (CPU) is used to receive, process, and forward data.

[0046] The external interface is used to connect the main control computer and the central processing unit to realize data transmission and reception.

[0047] The access point units are interconnected through photoelectric converter groups;

[0048] Directional antennas have a strong directional gain pattern, and all directional antennas can cover narrow channels.

[0049] The directional antenna is connected to the radio frequency (RF) chip, which amplifies and modulates the signal and converts the RF signal into a digital signal that can be recognized by the I / O port, providing it to the central processing unit.

[0050] The radio frequency (RF) chip connects to the central processing unit (CPU) via I / O ports, converts the bit stream sent by the CPU into RF signals and transmits them through a directional antenna, and converts the RF signals received on the directional antenna into bit streams and sends them to the CPU.

[0051] The optoelectronic converter group includes at least one pair of optical fiber transceiver ports and one pair of electrical transceiver ports; the optoelectronic converter groups are connected to each other via optical fibers, thereby realizing the sequential connection of access point units; the optical fiber transceiver ports are connected to one end of the optical fiber, and the other end of the optical fiber is connected to the optical fiber transceiver ports of other access point units, and the wireless access devices exchange data through the optical fiber; the electrical transceiver ports are connected to the central processing unit; the optical fiber can be connected across access point units, so that the failure of some access point units does not affect the operation of the entire network.

[0052] like Figure 2 As shown, the connection methods of access point units include simple series, parallel series, bidirectional series, and hybrid series. Among them: simple series is used when the goal is to save fiber, and each access point can use only one pair of fiber ports for simple series connection; parallel series is used when the goal is to improve reliability, and each access point can use multiple pairs of fiber ports for parallel series connection, with the data flow direction being the same; bidirectional series is used when the goal is to reduce latency, and each access point can use two pairs of fiber ports for bidirectional series connection, with the data flow direction being opposite; in addition, hybrid series can be used, which increases the number of connected fibers for access point units that are difficult to maintain on the basis of simple series connection, thereby enhancing the performance of part of the network, but the network topology can always be decomposed into a finite number of unidirectional loops.

[0053] This embodiment provides an access method for a wireless access device. When a mobile terminal approaches an access point unit K, it establishes a bidirectional wireless connection with the access point unit K. Data is transmitted bidirectionally through a wireless channel and forwarded to each other by access point units connected by optical fibers, thereby enabling communication between the mobile terminal and the host computer.

[0054] The communication process and forwarding rules between the mobile terminal and the main control computer are as follows:

[0055] A1: When the mobile terminal approaches the access point unit K, it sends uplink data to the access point unit K through the radio frequency link and receives downlink data from the access point unit K through the radio frequency link.

[0056] Mobile terminals achieve positioning by measuring the signal power of different access point units, that is:

[0057]

[0058] in, , These are the signal power measured by the mobile node to access point m and access point n, respectively. This is the coefficient for signal attenuation with distance. The distance between access points m and n and These represent the distances between the mobile terminal and access points m and n, respectively, which are the one-dimensional positioning results. It can be measured in advance, or estimated by adjacent access devices through bidirectional ranging methods after the network is built, such as round-trip time ranging and signal strength ranging methods. This can be obtained through data fitting, as shown in this embodiment. .according to and The size of the signal determines which access point the mobile terminal will connect to. However, the mobile terminal's positioning still depends on the measurement of the signal power between the two nodes.

[0059] A2: Any access point unit determines the data forwarding direction based on the network topology and completes the data forwarding;

[0060] Obtaining network topology includes:

[0061] The master computer sends a network test command, enabling all access point units to obtain complete network topology information, specifying the shortest hop count, and defining the process and forwarding rules as follows:

[0062] B1: The main control computer connects to the access point unit K. The access point unit K outputs a network test frame header and adds its own ID.

[0063] B2: After receiving the network test frame, other access point units add their own ID and forward it to the next level;

[0064] B3: Access point unit K terminates forwarding when it observes its own ID twice from the received network test frame;

[0065] Any access point unit can determine the distance to the target access point by receiving network test frames, that is, the distance between its own ID and the target access point ID.

[0066] Obtaining the distance to the target access point allows the access point unit to determine the data forwarding direction. For example, in a bidirectional serial connection, if node 1 needs to communicate with node 2, it can either forward the data to the right to node 2 or forward it to the left through nodes 4 and 3, finally reaching node 2. However, forwarding to the right is clearly shorter and has less latency. Therefore, the shortest data forwarding distance can be obtained by determining the distance to the target access point.

[0067] A3: When the access point unit K, which is directly connected to the main control computer, receives data, the central processing unit sends the data to the main control computer through the external interface.

[0068] This invention divides long, narrow channels into multiple segments, covers each segment of the narrow channel with a directional antenna on a wireless access device, and connects the wireless access devices with optical fibers; it reserves a backup optical interface, supports multiple connection methods, and designs a dedicated network configuration frame, thus solving the problems of high deployment cost and poor reliability of existing wireless routers or base stations in narrow channel environments.

[0069] This invention employs a low-speed serial optoelectronic interface as the data carrier, significantly reducing device cost and better adapting to the low-speed, high-reliability requirements of control and monitoring scenarios. The network adopts a simple serial architecture with a simple forwarding protocol and low data latency. Dedicated network test frames can be designed to allow access points to obtain complete network topology information. The device provides a backup optical interface, which can improve network reliability or reduce latency through different fiber optic connection methods. The device supports one-dimensional wireless positioning. The directional antenna achieves columnar signal coverage, adapting to narrow channel environments and improving energy efficiency.

[0070] Based on the above, the core design and advantages of this invention are as follows:

[0071] 1. The network topology is simple. The serial network covering the narrow channel has no redundant branches. The data forwarding rules are simple and the network test frame can enable all access points to obtain complete network topology information, which is convenient for data forwarding and network fault detection.

[0072] 2. Diverse networking methods: Without changing the access device, by changing the fiber optic connection method, simple serial, parallel serial, bidirectional serial, and hybrid serial methods can be achieved to achieve the focus on hardware cost, reliability, and latency indicators.

[0073] 3. The application of directional antennas to cover narrow channels increases communication energy efficiency and reduces the number of access devices required;

[0074] 4. A dedicated low-complexity wireless positioning algorithm was designed for one-dimensional network structures, allowing mobile terminals to know their location through wireless communication with multiple access point units.

[0075] 5. When using parallel serial or bidirectional serial, there are at least two available multi-hop fiber optic channels between any access point unit and the main control computer. Even if one fails, the communication network can still work normally.

[0076] 6. The wireless access device avoids expensive PHY chips, RJ45 interfaces and transformers, high-speed optical modules and high-speed signal processors. It can use only low-cost microcontrollers, serial-to-optical modules and serial-to-USB chips as the core components of the system, reducing equipment costs and failure rates.

[0077] Example 2:

[0078] To verify the effectiveness of the present invention, the wireless access device provided in Embodiment 1 is used in a tunnel in this embodiment, as follows:

[0079] In this embodiment, the radio frequency chip is an nRF2401, which is connected to the central processing unit via an SPI interface; the external interface is based on a serial-to-USB chip, which is connected to the host computer via a USB interface; the central processing unit is a microcontroller or FPGA with multiple serial ports; each directional antenna covers a section of the tunnel, and all directional antennas can cover the entire tunnel; the mobile terminal is a robot.

[0080] Reference Figure 1 In this embodiment, the main control computer sends data to the central processing unit (CPU) of a designated access point unit via a USB interface. The data is converted into a serial signal and then distributed by the CPU to the photoelectric converter group. This signal is then converted into an optical signal and transmitted to other access point units via optical fiber. Upon receiving the signal at their optical fiber transceiver ports, the photoelectric converter groups at other access point units forward the signal to the next-level access point unit, until the data reaches the access point unit where the robot is located. Data transmission to the mobile terminal is then completed via the radio frequency (RF) channel. Similarly, the robot can send data via the RF channel, which is then forwarded by the access point units and ultimately reaches the main control computer. Furthermore, data can be transmitted between access point units via a serial multi-hop optical fiber channel.

[0081] like Figure 2As shown, this embodiment provides four networking methods for access devices: simple serial, parallel serial, bidirectional serial, and hybrid serial. Simple serial uses only one pair of fiber optic transceiver ports for transmission and reception, with each access point using only two fibers to connect to other access points, resulting in the lowest cost. However, the failure of any fiber optic segment will cause network failure. Parallel serial utilizes two pairs of fiber optic transceiver ports for transmission and reception, with each access point unit using four fibers to connect to other access point units, including two transmit and two receive ports with the transmit / receive ports in the same direction. The network only fails when both transmit / receive fibers on an access point unit fail simultaneously, providing high reliability and allowing for rapid determination of bit errors by comparing data on the two optical receive ports. Bidirectional serial utilizes two pairs of fiber optic transceiver ports for transmission and reception, with each access point unit using four fibers to connect to other access point units, including two transmit and two receive ports with the transmit / receive ports in different directions. This allows access point units to select the data forwarding direction based on the network topology, minimizing the total hop count and reducing latency. Hybrid serial adds fibers to nodes that are difficult to maintain (such as nodes deep in tunnels) on top of simple serial, reducing their failure rate.

[0082] like Figure 3 As shown, this embodiment provides a network testing method designed to enable all access point units to identify simple serial, parallel serial, and bidirectional serial networks through two data forwardings, thereby obtaining serial network topology information. In this embodiment, the master control computer is connected to access point 2 and can send AT as the network test frame header. After receiving the network test frame, each access point adds its own ID and forwards it to the next level. Access point 2 terminates forwarding when it observes its own ID twice in the received frame. At this point, all access points can calculate their distance to the target access point, i.e., the hop count, from the last forwarded network test frame.

[0083] like Figure 4 As shown, this embodiment provides a one-dimensional positioning method for a robot, aiming to determine the distance between the robot and the two nearest access points without needing to know the transmission power. For example, assuming the robot is between access point 3 and access point 4, the signal power of access points 3 and 4 can be measured and denoted as follows: , The distance between the robot and access point 3 is denoted as d3, the distance between the robot and access point 4 is denoted as d4, and the distance between access point 3 and access point 4 is denoted as... Since it is a one-dimensional, narrow tunnel, we can assume... It is known that the received signal power h is inversely proportional to a power of the link distance d, i.e.

[0084]

[0085] in, It is a constant related to antenna gain and transmit power. Let be the coefficient of signal attenuation with distance; then we can know

[0086]

[0087] Further, we can obtain

[0088]

[0089] The distances d3 and d4 between the robot and access points 3 and 4 are expressed as signal power. and and known quantities The function.

Claims

1. A wireless access device for narrow channels, characterized in that, It includes multiple access point units connected in sequence, and the access point unit includes: Directional antennas are used to achieve signal coverage in a specified channel area; A photoelectric converter group is used to perform photoelectric / electro-optical conversion of serial signals; Environmental sensors are used to monitor the environment within the channel; The central processing unit (CPU) is used to receive, process, and forward data. The external interface is used to connect the main control computer and the central processing unit to realize data transmission and reception. The access point units are interconnected through a group of photoelectric converters. Access method of wireless access device: When the mobile terminal is close to a certain access point unit K, a two-way wireless connection is established with the access point unit K. Data is transmitted bidirectionally through the wireless channel and forwarded to each other by the access point units connected by optical fiber, so as to realize the communication between the mobile terminal and the host computer. The communication process and forwarding rules between the mobile terminal and the main control computer are as follows: A1: When the mobile terminal approaches the access point unit K, it sends uplink data to the access point unit K through the radio frequency link and receives downlink data from the access point unit K through the radio frequency link. A2: Any access point unit determines the data forwarding direction based on the network topology and completes the data forwarding; A3: When the access point unit K, which is directly connected to the main control computer, receives data, the central processing unit sends the data to the main control computer through the external interface; The acquisition of network topology in step A2 includes: The master computer sends a network test command, enabling all access point units to obtain complete network topology information, specifying the shortest hop count, and defining the process and forwarding rules as follows: B1: The main control computer connects to the access point unit K. The access point unit K outputs a network test frame header and adds its own ID. B2: After receiving the network test frame, other access point units add their own ID and forward it to the next level; B3: Access point unit K terminates forwarding when it observes its own ID twice from the received network test frame; Each access point unit determines the distance to the target access point by receiving network test frames, that is, the distance between its own ID and the target access point ID.

2. The wireless access device for narrow channels according to claim 1, characterized in that, The directional antenna is connected to the radio frequency chip, which is used to amplify and modulate the signal, and convert the radio frequency signal into a digital signal that can be recognized by the I / O port, and provide it to the central processing unit.

3. A wireless access device for narrow channels according to claim 1, characterized in that, The photoelectric converter group includes at least one pair of optical fiber transceiver ports and one pair of electrical transceiver ports.

4. A wireless access device for narrow channels according to claim 3, characterized in that, The photoelectric converter groups are interconnected via optical fibers, thereby enabling the sequential connection of access point units.

5. A wireless access device for narrow channels according to claim 4, characterized in that, The connection methods of the access point units include simple series, parallel series, bidirectional series, and hybrid series, wherein: Simple cascading: Each access point unit uses only one pair of fiber optic ports for cascading. Parallel serial connection: Each access point unit uses multiple pairs of fiber optic ports connected in parallel, with the data flow direction being the same. Bidirectional serial connection: Each access point unit uses two pairs of fiber optic ports for bidirectional serial connection, with data flow directions in opposite directions; Hybrid cascading increases the number of optical fibers connected to access point units that are difficult to maintain, based on simple cascading.

6. A wireless access device for narrow channels according to claim 1, characterized in that, In step A1, the mobile terminal achieves positioning by measuring the signal power of different access point units, that is: ； in, , These are the signal power measured by the mobile node to access point m and access point n, respectively. This is the coefficient for signal attenuation with distance. The distance between access points m and n. and These represent the distances between the mobile terminal and access points m and n, respectively, which are the one-dimensional positioning results.

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